Heat exchanger header with deformations

ABSTRACT

The present invention has its object to provide a heat exchanger with plastic tanks type, wherein a seal member is regularly compressed and hooks or tabs of header core crimped in a uniform fashion. Deformations predominantly located in the large sides or sides adjacent to the tank foot of the header, are formed and distributed in the inner or outer wall. The deformations in the periphery, or more particular, on the outside of the header wall, are formed after the brazing process.

This patent application claims priority of provisional application No.60/635,215 filed Dec. 10, 2004

FIELD OF THE INVENTION

The present invention relates to the field of heat exchangers, and, inparticular, heat exchangers with plastic tanks.

BACKGROUND OF THE INVENTION

Modern heat exchangers are often made of aluminum or aluminum alloy, atleast in their core and header portions. Aluminum heat exchangers oftenuse plastic end tanks or manifolds that are mechanical assembled by abending or crimping process. The crimp most often consists of adeformation on the header tabs that produces an interference with theplastic tanks. This allows the assembly of header plus end tank in a wayto produce a hermetically sealed or hermetic system by compressing arubber seal (gasket) in this area to form a seal. By assembly in thismanner, the heat exchanger is able to stay sealed and support evenelevated internal pressures during the operation of the heat exchanger.Examples of prior art heat exchangers are found in U.S. Pat. No.4,461,348 Jul. 24, 1984, Toge et al, with FIGS. 1-4 showing the crimped‘hooks’, tank feet and header positioning in radiators.

Aluminum braze processes used in the production of heat exchangers havemany advantages, but also have the disadvantage that the strength gainedduring the cold (non thermally-heated) work of the header is lost due tothe re-crystallization of micro structures during the brazing. Materialgets a normalization status.

In order to resist the stresses produced by the pressure, thickermaterials have been used. However, these thicker materials mean asignificantly negative impact from both a cost and a crimping processpoint of view.

Generally, conventional radiators for automotive engines are composed ofa core unit having metallic tubes and corrugated fins connected witheach other by welding in a heat transmitting manner, and an upper and alower core plate or header connected to both ends of the tubes. Each ofthe core plates or headers is formed with a holding groove along itsperiphery.

BRIEF DESCRIPTION OF THE INVENTION

In view of the above disadvantages of the prior art, preferredembodiments of the present invention provide a heat exchanger, wherein aseal member is regularly compressed and tabs or hooks of headers arebent (crimped) in a uniform fashion.

A heat exchanger of the present invention is preferably a heat exchangeruseful in automotive application, more preferably a radiator or chargerair cooler, (CAC), more preferably a charge air cooler or the like.Preferred embodiments of the present invention useful in automotivevehicles, are heat exchangers with cores and headers made of aluminum oraluminum alloys in processes such as the CAB process, that has a header(collector) with side wall on its periphery for receiving a seal memberas well as a plastic tank member, wherein deformations (for example inthe large sides of the side wall) are presented in the inner or outerwall. Non limiting examples of deformations can include notches,grooves, or protuberances, elevations, ribs, or the like depending whichcan be present on the interior or exterior of the tank. The deformationsin the periphery of the header wall are preferably made after thebrazing process. This prevents the reduction of the stiffness gained onthe hardening of the stamping in cold work, and associated increase inproduct life span.

As stated above, preferred embodiments of the present invention relateto a heat exchanger, and more particularly a heat exchanger with plasticend tanks, having particular use in radiator or charge air coolerapplications, as a radiator or charger air cooler dissipating heat fromcooling fluid for engines or gas, preferably, air from the turbochargers of automotive vehicles.

Preferred embodiments of the present invention provide additionalstrength to the headers of the core, without using the solutions such asoverall thickening of materials. The header has a header portionconnected to or otherwise attached or fixed (hereinafter ‘fixed’) to thecore portion. The present invention advantageously provides a method forincreasing the strength of the materials without such thickening, whileretaining the advantage of increased pressure resistance and increaseddurability of the heat exchanger, even under repetitive cycles ofpressure.

The durability of the heat exchangers with this type of design,preferably with plastic tanks, depends to a large extent on the strengthof the crimping. Stresses produced by the internal pressure on the heatexchanger are distributed along the periphery of the header. The headertabs that hold the tanks, and, subsequently, the seat of the header,suffer stress. This effect is more significant when size increases, i.e.size of the tanks, width and height are larger.

The present invention provides for a way of strengthening or reinforcingarea of or around the header joint of heat exchanger assemblies. Thepresent invention, by providing for deformations, such as grooves,notches, projections or deformations, on the header, and, in particulargrooves or notches, in or on the side wall of the header, increase thestiffness of the side wall. This increase in stiffness consequentlyproduces additional strength at the header to tank joint to a level thateven in highly elevated stress and pressure conditions, the crimpingjoint, is able to resist (not burst or otherwise bulge) to an extentwhere it withstands the internal pressure, and the heat exchanger headerto joint remains intact.

Preferred embodiments of the present invention, therefore, provide forincreased pressure resistance at the header to tank joint, particularlyat the header to tank crimp joints, of the heat exchanger without anysubsequent increase in material thickness. In more preferredembodiments, the overall material thickness, particularly in the headerside wall, can even be reduced proportionally without any significanteffect on pressure resistance.

Preferred embodiments of the present invention also foresee adaptationsand/or modification of the process operations for making heat exchangerassemblies. In preferred methods of the present invention, in the stepsof the process operation, at least one deformation, and, preferably, aplurality of deformations is added to the header side wall after, in thecase of brazed headers, the brazing process, without major effect oneither the timing or effectiveness of the heat exchanger assemblyprocess.

In preferred method embodiments of the present invention, the process tobuild the deformations into to the header material is done with asubsequent increase the strength of the header physical properties. Inmost preferred embodiments, this deformation addition step in theprocess must be performed after the brazing to obtain the maximumadvantage. Preferred process operations produce deformations on theheader side walls of the core. These deformations increase the strengthof the core to resist pressure to a greater degree, especially underareas of high stress, than non-deformed header side walls. As describedabove, the processes in accordance with the present invention producedeformations, such as ribs projections, or the like, particularlydeformations on the side walls of the header that increase stiffness ofthe material.

The deformations on the side walls of the header are, preferably, formedby applying pressure or ‘compressing’ on the exterior or interior,preferably from the exterior surface towards the interior surface, topush the deformations inward in the header. Such deformations arepreferably formed such that the deformations extend into the surface orare inward facing as opposed to projecting out of or outward facing theouter surface of the side walls of the header. Deformations on the sidewalls of the header are also spaced in a fashion to provide maximumsupport for the heat exchanger core at the header to tank joint. Mostpreferred are deformations that extend inwardly towards the interior ofthe header. Also most preferred are deformations that are formed afterbrazing, particularly in aluminum based cores with headers.

The deformations are even more preferably spread out on the side wall ateither regular or irregular intervals along the side wall. Mostpreferably the deformations are spread out at intervals such that atleast one of the deformations occurs at an area of the radial area ofthe header. Where a header is crimped with tabs or hooks (hooks) to aplastic tank, deformations are also even more preferably located atleast one area at or near the hooks of the header that are crimped ontothe plastic tanks.

In preferred embodiments of the present invention, the deformations areadded to the header side wall at the area where the plastic tank foot iscrimped onto, or a joint is formed between, the tank foot and theheader. Areas of high stresses and under internal pressure of the heatexchanger often occur at the area of the header, tank foot and thegasket seal between the foot and the header of the core. Preferably, thedeformations of the present invention are located along the header sidewall that runs on the side of or essentially parallel with, or at leastadjacent to the tank foot above the area of the gasket seal, or at thearea of highest stress at the folds of the side wall if there arecrimped joints.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional perspective outside view of the header withdeformations on the outer side of the wall.

FIG. 2 Is a cross sectional view of the deformations of FIG. 1 on theouter side of the header wall.

FIG. 3 Is a sectional perspective inside view of the header withdeformations shown originating from on the outer side of the wall.

FIG. 4 Is a sectional perspective outside view of the header withdeformations on the inner side of the wall.

FIG. 5 Is a sectional perspective e inside view of the header withdeformations on the inner side of the wall.

FIG. 6 Is a cross sectional view of the deformations on the inner sideof the header wall.

FIG. 7 Is a perspective view of a section of heat exchanger core, sealmember and tank member. This view reflects the deformations on the outerside of the header wall.

FIG. 8 is a perspective view of the header and tank joint as exists inthe prior art FIG. 9 is a perspective view of the arrangement and tankjoint as exists in the prior art.

FIG. 10 is a cross sectional view of deformations of FIG. 6 inaccordance with an aspect of the present invention.

FIG. 11 is a view of a header section with deformations of FIG. 1, inaccordance with an aspect of the present invention.

FIG. 12 is a view of the interior of a header where deformations areshown compressed into the header, in accordance with an aspect of thepresent invention.

FIG. 13 is a view of a foot to header joint with gasket, denoting wheredeformations would be added to conform with an aspect of the presentinvention, and with non crimped or unbended hooks.

FIG. 14 is a side view of an aluminum header of the prior art crimpedwith a plastic end tank foot.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-7, deformations (26) are added, preferably by ajig, to the side wall tab (hook) of the header (10). Interior surface ofheader (2) is shown.

As shown in FIG. 2 for the deformations made on the outer side of thewall Depth of the deformation (d), height (h) length (l) and width (w)(see also (w3) of FIG. 10) are measured to confirm adequate function.

In a preferred embodiment of the present invention, the (h) dimensioncan be from about 10% to the full size of the tooth (h1). The width (w)can be from 0.1 mm to the end of the curve of the inside radio (r) withthe intersection of the sealing surface (s). The depth (d) dimension canbe from about 0.1 mm to max of 50% of the material thickness of theheader core. Width (w3) can be from 0.2 mm to 3.0 mm, or otherwise,depending on the actual configuration of the heat exchanger.

Referring to FIGS. 3-7 are additional preferred embodiments of thepresent invention. The tab (6) is bent into the shape of a hook (6 a),is shown, with deformations (26) on header wall (30). Interior surfaceof wall (2) is also shown.

FIG. 6 represents a cross sectional view of a tank, preferredembodiments showing deformations and increased side wall strength.

FIG. 7 shows a perspective sectional view of the heat exchangeraccording to a preferred embodiment of the present invention. Theplastic tanks members (3), rubber seal members (4) and tube (5), thealuminum core header (2,) is fixed respectively by bending the tab ortooth (6) of the outside wall of the header (2) producing hook (6 a).This produces a plurality of hooks (6 a) on the outer side wall.

Referring to FIG. 8 is shown tubes (S) a prior art header wall (81) thatdoes not have deformations on the wall of the periphery. This prior artdesign is a less effective method to resist pressures into to heatexchanger. As shown in FIG. 9 when the prior art heat exchanger issubject to internal pressure the hooks (91) tend to open. The maximumstresses and deformation are produced at the zone marked in the circle Zof FIG. 9, and circle (d) of FIG. 13, during normal operation of heatexchanger. The rigidity (mechanical strength) of the outer wall of theheader core is increased. In preferred embodiment of the presentinvention, deformation of the hooks (91) is reduced, thereby increasingthe life of the heat exchanger to repetitive pressures.

Referring to FIG. 10, a cross sectional view of the deformations inshown, with deformations depth of and deformation width (w) illustrated.A slight distortion (y) on the inner surface of the header at the portof the deformations is shown.

Referring to FIG. 11 is a view of the header section (110) showingdeformations X1, X2 as reinforcement.

Referring to FIG. 12 is interior section of header (13) wheredeformations have been pushed in from exterior (12) are shown in CACheader with deformations (10) and plastic end tank (11) with tankcrimped onto header.

Referring to FIG. 13 is shown a plastic tank (A) with foot joint (A′),header side wall with rib added (B) and the area of the crimping (C)generated by a non-bended tooth type crimping, deforming a side wallagainst a plastic tank wall to produce a hook. Area of high stress anddeformation under internal pressure of the heat exchanger located atarea (D). Gasket (seal) (E) is also illustrated.

Referring to FIG. 14 is shown a typical heat exchanger (40) with header(48) crimped to form a hook, and gasket (47) correctly positioned. Alsoshown are tube (41), turbulator (43), tub assembly (46), fin (45), sideplate (44) and end tank (42).

Unless stated otherwise, dimensions and geometries of the variousstructures depicted herein are not intended to be restrictive of theinvention, and other dimensions or geometries are possible. Pluralstructural components can be provided by a single integrated structure.Alternatively, a single integrated structure might be divided intoseparate plural components. In addition, while a feature of the presentinvention may have been described in the context of only one of theillustrated embodiments, such feature may be combined with one or moreother features of other embodiments, for any given application. It willalso be appreciated from the above that the fabrication of the uniquestructures herein and the operation thereof also constitute methods inaccordance with the present invention.

The preferred embodiment of the present invention has been disclosed. Aperson of ordinary skill in the art would realize however, that certainmodifications would come within the teachings of this invention.Therefore, the following claims should be studied to determine the truescope and content of the invention.

1. A brazed heat exchanger comprising; a plastic tank having a flange orfoot portion at its open end; a core portion having a plurality oftubes; and at least one header; a header portion of the at least oneheader having a side wall, a bottom wall and an outer side wall formingan area for receiving the flange or foot portion fixed to the coreportion; a plurality of hooks extending from the outer side wall of theheader portion; a basically leak tight tank to header joint; a sealmember disposed in between the wall area and the foot portion and theheader; and at least one deformation in the side wall of the headerportion; wherein the header portion foot portion and sealing member formthe basically leak tight tank to header joint, and wherein the hooks arecrimped over the flange or foot portion to fix the tank member to theheader to form the tank to header joint.
 2. A heat exchanger as claimedin claim 1, wherein the increased stiffness in the side wall causesincreased resistance to stress at the tank to header joint.
 3. A heatexchanger as claimed in claim 1, wherein the compressed deformation isformed by compressing the outer surface of the side wall after theformation of the tank to header joint.
 4. A heat exchanger as claimed inclaim 3, wherein the compression is achieved by using a specialized toolor jig.
 5. A heat exchanger as claimed in claim 1, wherein the coreportion and header portion are formed by a brazing process.
 6. A heatexchanger as claimed in claim 5, wherein the deformation is formed afterthe brazing process.
 7. A heat exchanger as claimed in claim 6, whereinthe core portion and header portion are made of aluminum or aluminumalloy.
 8. A heat exchanger as claimed in claim 7 wherein the heatexchanger is a charge air cooler.
 9. A heat exchanger as claimed inclaim 3, wherein the heat exchanger is a radiator.
 10. A heat exchangercomprising at least one plastic end tank with a foot, at least onesealing member, at least one aluminum or aluminum alloy heat exchangercore having a central core portion and a header having side walls,wherein at least one deformation is formed on the side walls of theheader portion at an area where a side wall is in contact with the tankfoot.
 11. A heat exchanger as in claim 10, having a plurality ofdeformations distributed in the inner or outer wall of the header.
 12. Aheat exchanger as claimed in claim 11, where the deformations are in theperiphery of the header wall.
 13. A heat exchanger as claimed in claim12 wherein the deformations are made after the brazing process.
 14. Aheat exchanger as claimed in claim 11 wherein the deformations areformed so that they are compressed inwardly or toward the interior ofthe header core.
 15. A heat exchanger as claimed in claim 14 wherein theheat exchanger core is brazed after the deformations are formed afterbrazing.
 16. A method for making a reinforced brazed heat exchangerassembly by: forming a heat exchanger core by assembling tubes, fins,header portions with a holding groove and a bottom and side wall for acontaining a tank foot, together as one unit; brazing the heat exchangercore by conventional brazing techniques in order to form a basicallyleak proof unit; compressing a plurality of deformations into the sidewall of the header aligned with the tank foot after the brazing step;attaching a plastic end tank or manifold with a foot to the headerportion of the unit; creating a leak tight seal by placing a seal memberor gasket in the holding groove; and joining a part of the headerportion so that it holds the tank foot in place; thereby reinforcing thestrength of the brazed heat exchanger assembly.
 17. A method for makinga reinforced brazed heat exchanger assembly as in claim 16, wherein thedeformations are compressed on the exterior surface of the side walltowards the interior surface of the side wall.
 18. A method for making areinforced brazed heat exchanger assembly as in claim 16, wherein themethod of joining is crimping.
 19. A method for making a reinforcedbrazed heat exchanger assembly as in claim 18, wherein the deformationsare compressed on the exterior surface of the side wall towards theinterior surface of the side wall.